From 34b4cf1a30f091cdf555b3080b8240b56a123f9a Mon Sep 17 00:00:00 2001
From: Stefano Avallone <stavallo@gmail.com>
Date: Thu, 23 May 2024 20:16:47 +0200
Subject: [PATCH] wifi: Use custom Shuffle implementation instead of
 std::shuffle

std::shuffle implementation is not guaranteed to return the same
permutation across different libraries
---
 src/core/test/random-variable-stream-test-suite.cc | 12 ++++++++----
 src/wifi/model/txop.cc                             |  3 ++-
 src/wifi/model/wifi-mac.cc                         |  3 ++-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/core/test/random-variable-stream-test-suite.cc b/src/core/test/random-variable-stream-test-suite.cc
index c2fd5015013..145bd49bd6f 100644
--- a/src/core/test/random-variable-stream-test-suite.cc
+++ b/src/core/test/random-variable-stream-test-suite.cc
@@ -2878,6 +2878,8 @@ BinomialAntitheticTestCase::DoRun()
  * \ingroup tests
  *
  * \brief Test the Shuffle function
+ *
+ * Check that the Shuffle function actually shuffles the elements and does so in a portable way.
  */
 class ShuffleElementsTest : public TestCase
 {
@@ -2896,7 +2898,11 @@ ShuffleElementsTest::ShuffleElementsTest()
 void
 ShuffleElementsTest::DoRun()
 {
+    RngSeedManager::SetSeed(1);
+    RngSeedManager::SetRun(1);
+
     auto rv = CreateObject<UniformRandomVariable>();
+    rv->SetStream(1);
 
     // test empty vector
     std::vector<uint8_t> vec{};
@@ -2916,7 +2922,6 @@ ShuffleElementsTest::DoRun()
     vec.push_back(1);
 
     Shuffle(vec.begin(), vec.end(), rv);
-    std::sort(vec.begin(), vec.end());
 
     NS_TEST_EXPECT_MSG_EQ((vec == std::vector<uint8_t>{1, 3}), true, "Expected vector {1, 3}");
 
@@ -2927,11 +2932,10 @@ ShuffleElementsTest::DoRun()
     vec.push_back(9);
 
     Shuffle(vec.begin(), vec.end(), rv);
-    std::sort(vec.begin(), vec.end());
 
-    NS_TEST_EXPECT_MSG_EQ((vec == std::vector<uint8_t>{1, 2, 3, 4, 7, 9}),
+    NS_TEST_EXPECT_MSG_EQ((vec == std::vector<uint8_t>{4, 1, 9, 3, 2, 7}),
                           true,
-                          "Expected vector {1, 2, 3, 4, 7, 9}");
+                          "Expected vector {4, 1, 9, 3, 2, 7}");
 }
 
 /**
diff --git a/src/wifi/model/txop.cc b/src/wifi/model/txop.cc
index 58f02cf513a..93c8e541824 100644
--- a/src/wifi/model/txop.cc
+++ b/src/wifi/model/txop.cc
@@ -30,6 +30,7 @@
 #include "ns3/attribute-container.h"
 #include "ns3/log.h"
 #include "ns3/pointer.h"
+#include "ns3/shuffle.h"
 #include "ns3/simulator.h"
 #include "ns3/socket.h"
 
@@ -665,7 +666,7 @@ Txop::Queue(Ptr<WifiMpdu> mpdu)
 
     // shuffle link IDs not to request channel access on links always in the same order
     std::vector<uint8_t> shuffledLinkIds(linkIds.cbegin(), linkIds.cend());
-    std::shuffle(shuffledLinkIds.begin(), shuffledLinkIds.end(), m_shuffleLinkIdsGen);
+    Shuffle(shuffledLinkIds.begin(), shuffledLinkIds.end(), m_shuffleLinkIdsGen.GetRv());
 
     if (!linkIds.empty() && g_log.IsEnabled(ns3::LOG_DEBUG))
     {
diff --git a/src/wifi/model/wifi-mac.cc b/src/wifi/model/wifi-mac.cc
index 9c27f1be546..393789671c1 100644
--- a/src/wifi/model/wifi-mac.cc
+++ b/src/wifi/model/wifi-mac.cc
@@ -36,6 +36,7 @@
 #include "ns3/log.h"
 #include "ns3/packet.h"
 #include "ns3/pointer.h"
+#include "ns3/shuffle.h"
 #include "ns3/string.h"
 #include "ns3/vht-configuration.h"
 
@@ -1562,7 +1563,7 @@ WifiMac::UnblockUnicastTxOnLinks(WifiQueueBlockedReason reason,
 
     // shuffle link IDs not to unblock links always in the same order
     std::vector<uint8_t> shuffledLinkIds(linkIds.cbegin(), linkIds.cend());
-    std::shuffle(shuffledLinkIds.begin(), shuffledLinkIds.end(), m_shuffleLinkIdsGen);
+    Shuffle(shuffledLinkIds.begin(), shuffledLinkIds.end(), m_shuffleLinkIdsGen.GetRv());
 
     std::stringstream ss;
     if (g_log.IsEnabled(ns3::LOG_FUNCTION))